Study of electromagnetic field propagation in microwave-heated magnetoplasmas of compact ion sources

This paper presents the study of electromagnetic wave propagation in anisotropic, lossy and strongly inhomogeneous magnetoplasmas of compact ECR-type ion sources. Due to the specific shape of the magnetostatic field (B-minimum configuration), no simple symmetries can be assumed: a 3D approach is then mandatory. The operating wavelength is comparable with cavity length (λ
_RF
~ L
_c
), hence the “resonator” effect of the metallic cylindrical cavity where the plasma itself is sustained by the microwaves cannot be neglected. In addition, the characteristic lengths of plasma parameters are often smaller than the wavelength, thus implying a full-wave approach in modeling and simulations. These plasmas have to be described by lossy spatially dispersive “hot” (ν
_φ
~ v
_th
) dielectric tensor in order to model the inner plasma modes conversion and plasma-waves. The paper describes in details the modeling strategy for both microwave-to-plasma coupling schemes and for advanced, microwave based diagnostics tools such as interferometry and polarimetry.